1. Field of the Invention
This invention relates to a joint device for coupling a cover with a scanner body and particularly to an improved joint device that has a pivot means to enable the cover to turn for open or close smoothly and that may be made with less material and cost.
2. Description of the Prior Art
Scanner is a widely used computer peripheral device nowadays. With explosive growth of computer utilization and continuous drop of computer price, how to keep the cost and price of the scanner low while still maintain sufficient function and quality becomes a great challenge to scanner producers.
For low price scanners now available in the market, they usually have a joining device for coupling the cover of the scanner with the scanner body. One of the such joining devices is fixing one edge of the cover to one side of the body like a hinge. When in use, another edge of the cover that is free may be lifted to turn about the hinged edge for open or close the cover. While it may function well for one page or thin document, it is awkward for scanning a thick document such as a book. In such a situation, the cover will be inclined slantly and not fully cover the scanning surface. Scanning light cannot be distributed evenly, and outside light source may create further light distribution problem on the scanning surface and results in poor scanning quality.
In order to resolve the aforesaid problem, a number of solutions have been introduced in the market place. One of such examples is to divide the cover in two or more foldable and hinged sections. The cover may be flexibly lifted to a height desired to suit different document thickness. Such structure will increase cost. For low price scanner, the foldable sections generally are limited to two. Its functional improvement is also limited.
Another conventional example is shown in FIGS. 1 and 2. The scanner body 1 has a plurality of pivot sockets 10 provided at a side wall 14 of the scanner. At the top surface of the body 1, a transparent board 12 is provided for supporting scanning document. The cover 2 mainly includes a cover plate 22 and a plurality of pivot means 20 located thereunder engageable with the pivot sockets 10. Each of the pivot means 20 has a pair of spaced legs 24 extended downward from the bottom of the cover plate 22 and joined by a foot 25 at the distal ends thereof. Below the foot 25, there is a stopper 26 fixedly located thereunder. Each of the pivot sockets 10 includes a pair of spaced upper openings 110 at the top and a pair of spaced slots 116 formed thereunder for accommodating the legs 24. In the pivot socket 10, there is a gap 113 which enable the foot 25 to pass through. For assembly, the pivot means 20 is held at a selected angle to enable the foot 25 to pass through the gap 113, then the cover 2 is turned to horizontal to lay upon the scanner body 1.
The pivot socket 10 further has a stop tongue 112 and a stop foot 115 located respectively above and below the gap 113 for preventing the pivot means 20 from disengaging with the pivot socket 10 when the cover 2 is horizontally laid on the scanner body. Inside the pivot socket 10, there is a through slot 114 formed in the inside wall of the socket 10. When in use, the stopper 26 is inserted in the through slot 114 which serves as a guard to limit the stopper 26 tilting position so that the cover 2 may be lifted and tilted to an angle desired. As the pivot socket 10 has ample interior space to allow the foot 25 moving up or down, the cover 2 may be held horizontal over the transparent board 12 even for scanning a thick document.
However it creates new problems. The through slot 114 must be formed in the inside wall of the pivot socket 10 to accommodate the stopper 26. It exposes scanner inside mechanism to ambient environment. The scanner mechanism may easily be contaminated by dusts and dirts seeping through the through slot 114 and results in downgrade of scanning quality or even scanner malfunction.
It is therefore an object of this invention to provide a joint device that has an improved pivot means which is simply structured and may prevent scanner inside mechanism from contamination by external dusts and dirts.
The joint device according to this invention includes at least one pivot socket located at a top portion of a side wall of the scanner body. The pivot socket has a pivot shaft located in a trough formed in the side wall. The trough has closed inner walls without communicating with interior of the scanner body. The pivot shaft has substantially rectangular crosssection with round corners and being shaped with two parallel flat upper and lower surfaces bordered by two curved side surfaces. The pivot socket further has a stopping flange extending from the top wall of the scanner body and above the trough.
The scanner cover has at least one engaging member located below a side edge for pivotally engaging with the pivot shaft. The engaging member looks like a narrow section of a rectangular duct but with a curved lower portion and a side slot at a side wall for the pivot shaft to pass therethrough.
When in use, the pivot shaft is pivotally housed in the engaging member which may be moved up or down so that the cover may also be moved up or down according to thickness of the scanning document. The cover may be kept horizontal against the scanning board to obtain best possible scanning quality. The engaging member may be turned about the pivot shaft smoothly at a selected angle during scanning operation. As the pivot socket does not lead to inside of the scanner body, scanning mechanism won""t be contaminated by outside dusts and dirts. Scanning quality may be maintained at high level even after long time of use.